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  • 1
    ISSN: 1590-3478
    Keywords: Multiple sclerosis ; Sexual function ; Symptom
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Sommario È noto che disfunzioni sessuali possono verificarsi in pazienti con sclerosi multipla (SM). Questo studio si propone di descriverne l'occorrenza attraverso una analisi longitudinale. Quarantanove pazienti (27 femmine e 22 maschi) con SM definita sono stati intervistati ed esaminati due volte a 5 anni di distanza. Il numero di pazienti con disfunzioni sessuali risultò significativamente aumentato (p=0.009) senza significative differenze tra maschi e femmine. I maschi presentavano usualmente uno o due sintomi di disfunzione sessuale mentre le femmine ne avevano frequentemente due o più. Si conclude che il rischio di disfunzioni sessuali aumenta nel tempo. Ulteriori studi sono necessari sulle possibilità di trattamento.
    Notes: Abstract Sexual dysfunction is known to occur in multiple sclerosis (MS). The purpose of the study is to describe the change in sexual function and symptoms in a longitudinal study. Forty-nine patients (27 females, 22 males) with definite MS were interviewed and examined with 5 years interval. The number of patients with sexual dysfunction increased significantly (p=0.009) and involved females and males equally. Males usually had 1 or two symptoms of sexual dysfunction, while females frequently had 2 or more symptoms. It is concluded that the risk of sexual dysfunction increases over time. Further studies in treatment possibilities are needed.
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  • 2
    ISSN: 1590-3478
    Keywords: Multiple sclerosis ; Pain ; Symptoms ; Treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Sommario L'occorrenza di sindromi dolorose acute (durata inferiore a 1 mese) o croniche (durata superiore a 1 mese) è stata indagata in 49 pazienti (22 maschi e 27 femmine) con sclerosi multipla definita. Ciascun paziente è stato esaminato due volte con un intervallo di 5 anni tra i due controlli. Tra il primo e il secondo controllo si è osservato un significativo aumento di sindromi dolorose acute e croniche comprendenti tensione e dolore alle estremità, spasmi, lombalgia, segno di Lhermitte e dolori neuralgici. Tale aumento si è verificato sia nei maschi che nelle femmine ed è particolarmente evidente nei pazienti con deterioramento e disabilità.
    Notes: Abstract Forty-nine (22 males, 27 females) patients with definite multiple sclerosis were examined twice with 5 years interval regarding acute (less than 1 month duration) and chronic (more than 1 month duration) pain syndromes. From the first to the second examination a significant increase was found in the number of acute and chronic pain syndromes, including tension and pain in the extremities, spasms, low back pain, Lhermitte's sign and neuralgia. The increase included both men and women. The increase was especially found in patients with deterioration of disability.
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  • 3
    ISSN: 1573-5117
    Keywords: Corophium ; Hydrobia ; intertidal mud flats ; microphallid trematodes ; phenology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phenology of microphallid trematodes within their intermediate hostpopulations has been studied on an intertidal mud flat. The parasites usethe mud snail Hydrobia ulvae and the infaunal amphipod Corophium volutatoras first and secondary intermediate host, respectively. Migratory shorebirdsact as final hosts. Our results show a general trend of decline in thedensity of infected intermediate hosts during both spring and autumn, whichcould mainly be ascribed to shorebird predation. During summer the densityof both infected snails and infected amphipods increased considerably, witha culmination in June within the snail population (1000 infectedm-2 and in August within the amphipod population (40 000infected m-2. This time lag in parasite occurrence could berelated to (1) the development time of larval trematodes within the snails,(2) higher ambient temperatures in late summer increasing parasitetransmission between snails and amphipods during this period, and (3) ageneral increase in the Corophium population during late summer. Fromsamples collected between 1990 and 1995 it is shown that microphallidtrematodes occasionally may give rise to mass mortality in the amphipodpopulation. The prerequisites for such an event are a high parasiteprevalence within the first intermediate host population and unusually highambient temperatures, facilitating parasite transmission to the secondaryintermediate host, C. volutator.
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  • 4
    ISSN: 1573-5192
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract This study had two main objectives: (1) to construct an extensive, explicit list of characters and character states that might serve as a starting point, and perhaps even a model, for the compilation of a more complete list of characters for all cestode taxa; and (2) to use this character list to generate a hypothesis of the phylogenetic relationships among species representing most of the tetraphyllidean, lecanicephalidean and diphyllidean genera. Specimens of one species in each of 48 genera of tetraphyllideans, eight genera of lecanicephalideans, the three genera of diphyllideans, two genera of proteocephalideans and two genera of trypanorhynchs, were examined as whole-mounts and sections, with light and scanning electron microscopy. A list of 120 morphological characters was compiled. Four phylogenetic analyses were conducted using PAUP* and/or NONA. The first was a comprehensive analysis with the 56 tetraphyllidean and lecanicephalidean species as ingroups and the remaining seven species as outgroups. The second was an analysis of the three diphyllidean species as ingroups and the two proteocephalidean and the two trypanorhynch species as outgroups. The third was an analysis of the eight lecanicephalidean species and the “tetraphyllideans” Echeneibothrium sp. and Pseudanthobothrium n. sp. as ingroups and an outgroup consisting of the seven species used as outgroups in the first analysis. In the fourth analysis, the ingroup consisted of the 14 hooked tetraphyllideans (onchobothriids), and the outgroup consisted of the seven species used as outgroups in the first analysis. The results of these analyses support the following phylogenetic hypotheses: The diphyllideans are monophyletic and Echinobothrium n. sp. and Macrobothridium sp. are more closely related to one another than either is to Ditrachybothridium macrocephalum. The tetraphyllideans, lecanicephalideans and proteocephalideans are more closely related to each other than they are to the diphyllideans or the trypanorhynchs. The ordinal status of the lecanicephalideans is dubious. The lecanicephalidean species are more closely related to some of the tetraphyllidean taxa than these tetraphyllidean taxa are to the remainder of the tetraphyllidean taxa. The proteocephalideans appear to belong within the tetraphyllidean clade. The “tetraphyllidean” species Echeneibothrium sp. and Pseudanthobothrium n. sp. are members of the lecanicephalidean clade. The position of “Discobothrium” n. sp. within the lecanicephalideans is dubious. Within the tetraphyllideans, the non-acetabulate species Litobothrium daileyi, Disculiceps galapagoensis and Cathetocephalus sp. are the most basal members of the group. The family Onchobothriidae is monophyletic, as it is currently defined. Within the onchobothriids, the uniloculate species are basal to the multiloculate species; the species with unipronged hooks are basal to the species with multipronged hooks. Although relationships among the phyllobothriids, as they are currently defined, remain poorly resolved, the family Phyllobothriidae is not monophyletic. These results suggest that some aspects of the classification of the lecanicephalidean and tetraphyllidean taxa require revision. However, such revision should be based on further analyses including a broader representation of the genera and species in these groups.
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  • 5
    ISSN: 1438-3888
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Digenetic trematodes are widespread among mud snails (Hydrobiidae) living in coastal lagoons and estuaries, but knowledge is generally lacking on their impact on these host organisms. We examined the survival rates of infected and non-infected experimental populations of two mud snail species,Hydrobia ventrosa (Montagu) andHydrobia neglecta Muus, exposed to desiccation, freezing and anoxia in the laboratory. Our experiments indicated that non-infected groups of both species had similar survival rates after being subjected to desiccation and anoxia, whereasH. ventrosa survived freezing better thanH. neglecta. However, infected groups ofH. neglecta specimens subjected to desiccation showed significantly lower survival rates than non-infected groups. Infected and non-infected snails of both species exposed to freezing and anoxia exhibited similar survival rates. The possible mechanisms by which parasites influence their hosts are discussed. It is unlikely that the parasites in the present case mediate the coexistence of the twoHydrobia-species, because the snail with the highest reproductive effort-H. neglecta-showed lower infection rates in situ than its congenerH. ventrosa.
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 7982-7992 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An analytical model of a unit cell and of an array of field emitters with a distribution of tip radii is used to estimate the total current and current characteristics on the basis of geometry and materials. Based on the unit cell modeling, analytical estimates of ring cathode inductance, resistance, and capacitance are made to estimate the drive power required to sinusoidally modulate the array in order to produce a bunched electron beam. For a configuration of parameters indicative of a next generation field emitter array (FEA) ring cathode, the characteristics of the array are used to estimate the gain, efficiency, power output, and optimized length of an emission-gated Twystrode (TWT) using a simple model of the beam-wave interaction. The integrated analytical approach and its numerical implementation ("Cassandra") are validated by comparison to a 1D TWT code (CHRISTINE) which estimates the output power and the optimized length of a TWT. Using "Cassandra," it is shown that with next generation FEA parameters, interesting and significant levels of performance may be anticipated for a compact, broadband rf inductive output amplifier; in particular, an electronic efficiency of 32% with 15 dB gain may be possible from an array producing 260 mA peak and 71 mA average current at 10 GHz modulation using a helix 1.51 cm long.
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  • 7
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Microfabricated field emitter arrays (FEAs) can provide the very high electron current densities required for rf amplifier applications, typically on the order of 100 A/cm2. Determining the dependence of emission current on gate voltage is important for the prediction of emitter performance for device applications. Field emitters use high applied fields to extract current, and therefore, unlike thermionic emitters, the current densities can exceed 103 A/cm2 when averaged over an array. At such high current densities, space charge effects (i.e., the influence of charge between cathode and collector on emission) affect the emission process or initiate conditions which can lead to failure mechanisms for field emitters. A simple model of a field emitter will be used to calculate the one-dimensional space charge effects on the emission characteristics by examining two components: charge between the gate and anode, which leads to Child's law, and charge within the FEA unit cell, which gives rise to a field suppression effect which can exist for a single field emitter. The predictions of the analytical model are compared with recent experimental measurements designed to assess space charge effects and predict the onset of gate current. It is shown that negative convexity on a Fowler–Nordheim plot of Ianode(Vgate) data can be explained in terms of field depression at the emitter tip in addition to reflection of electrons by a virtual cathode created when the anode field is insufficient to extract all of the current; in particular, the effects present within the unit cell constitute a newly described effect.
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 3941-3943 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Dark, nonemissive defects form on the metal cathode in most molecular organic and polymer-based light emitting devices and eventually lead to the failure of the device. These defects have been characterized in situ using optical microscopy and ex situ using atomic force microscopy and Auger electron spectroscopy. On the basis of these observations, an electromigration mechanism for the formation of dark spot defects is proposed. The high current density required to operate polymer-based light emitting devices leads to electron-induced diffusion of the Al cathode when a short circuit forms in the emissive polymer layer. This process results in a "pileup'' of metal at the short circuit (anode) and a surrounding circular region where the Al is depleted, appearing as a dark spot on the cathode. © 1996 American Institute of Physics.
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  • 9
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The performance characteristics of rf power amplifiers will be significantly enhanced if a cathode source capable of producing current densities greater than 10 A/cm2 under gigahertz modulation can be created. Characterization of single- and multiple-tip arrays is imperative to determine performance characteristics in order to design and implement inductive output amplifiers (IOA): knowledge of the beam spread is paramount in the design of the helix or cavity power extraction region. Nevertheless, a simple analytic model for gated field emitters for understanding the spatial dispersion of the emitted electrons has not emerged. We provide such a model, approximating the tip by a smooth sphere and the gate by a ring of charge (Saturn model), and correlate it with experimental measurements made on a single Spindt-type molybdenum field emitter using a nanofabricated anode whose position from the emitter was determined using laser interferometry. Methods used to correlate theory with experiment are explained, and the dependence of the beam profile on tip sharpness, gate diameter, anode distance, and tip work function are examined. There is good agreement between theory and experiment. Measurement has shown that the rms spread angle is between 15° and 29°.
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 3569-3571 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a complete analytical treatment of elliptical field emitting structures in a diode geometry which correctly includes image charge effects off axis and the variation of field along the tip. The methodology may be extended to other geometries. The angular distribution of electron emission along the tip, the total emitted current, and the area factor may all be calculated as a function of emitter to anode distance, tip radius, tip height, and the anode-tip voltage difference. We show not only where errors arise if the planar Fowler–Nordheim (FN) equation is used to govern electron emission, but also how the FN equation may be modified to correctly address the complications due to atomically sharp tips. Finally, we present an analytic form of the area factor and compare it to the exact calculation and the various approximations. © 1995 American Institute of Physics.
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